Editing Freeview (UK) (section)

====Technical====
The [[Digital TV Group]] publishes and maintains the UK technical specification for high-definition services on digital terrestrial television (Freeview) based on the new DVB-T2 standard. The specification is known as the [[D-book]]. Freeview HD is the first operational TV service in the world using the [[DVB-T2]] standard. This standard is incompatible with DVB-T, and can only be received using compatible reception equipment.<ref>{{cite web|url=http://www.ofcom.org.uk/media/news/2008/04/nr_20080403b |title=More choice and new services on digital terrestrial TV |publisher=Ofcom |date=3 April 2008 |url-status=dead |archive-url=https://web.archive.org/web/20090711215852/http://www.ofcom.org.uk/media/news/2008/04/nr_20080403b |archive-date=11 July 2009  }}</ref> Some television receivers sold before the HD launch claimed to be "HD-ready", but this usually implies that the screen can display HD, rather than that DVB-T2 signals can be received{{snd}} a suitable tuner (typically built into a STB or PVR) is additionally required. Freeview HD set-top boxes and televisions are available. To qualify for the Freeview HD logo, receivers will need to be [[IPTV]]-capable and display Freeview branding, including the logo, on the electronic programme guide screen.<ref name="Freeview HD goes live">{{cite web|url=http://www.reghardware.co.uk/2009/12/03/freeview_hd_launch_report/|title=Freeview HD goes live|publisher=Register Hardware|date=3 December 2009|access-date=3 December 2009|archive-date=12 February 2010|archive-url=https://web.archive.org/web/20100212202900/http://www.reghardware.co.uk/2009/12/03/freeview_hd_launch_report/|url-status=dead}}</ref> The Freeview HD trademark requirements state that any manufacturer applying for the Freeview HD logo should submit their product to the [[Digital TV Group]]'s test centre (DTG Testing) for conformance testing.

On 2 February 2010, [[Vestel]] became the first manufacturer to gain Freeview HD certification, for the Vestel T8300 set top box.<ref>{{cite web |url=http://www.pressreleasepoint.com/vestel-receives-first-freeview-hd-certification|title=Vestel Receives First Freeview HD Certification|publisher=PressReleasePoint|date=2 February 2010}}</ref> [[Humax]] released the first Freeview HD reception equipment, the Humax HD-FOX T2, on 13 February 2010.<ref>{{cite web |url=http://www.broadbandtvnews.com/2010/02/15/first-dvb-t2-receiver-in-uk-stores/|title=First DVB-T2 receiver in UK stores|publisher=Broadband TV News|date=15 February 2010}}</ref>

It was announced on 10 February 2009, that the signal would be encoded with [[H.264/MPEG-4 AVC|MPEG-4 AVC]] High Profile Level 4, which supports up to 1080i30/1080p30, so 1080p50 cannot be used.<ref>{{cite web|url=http://www.dtg.org.uk/news/news.php?id=3270|title=Ofcom opts for AVC 4.0 for UK HD DTT|publisher=The Digital TV Group|date=10 February 2009|access-date=13 February 2009|archive-date=13 February 2009|archive-url=https://web.archive.org/web/20090213073716/http://www.dtg.org.uk/news/news.php?id=3270|url-status=dead}}</ref> The system has been designed from the start to allow regional variations in the broadcast schedule. Services are statistically multiplexed{{snd}} bandwidth is dynamically allocated between channels, depending on the complexity of the images{{snd}} with the aim of maintaining a consistent quality, rather than a specific bit rate. Video for each channel can range between 3&nbsp;Mbit/s and 17&nbsp;Mbit/s. [[Advanced Audio Coding|AAC]] or [[Dolby Digital Plus]] audio is transmitted at 384&nbsp;[[kb/s]] for 5.1 surround sound, with stereo audio at 128–192&nbsp;kbit/s; audio description takes up 64&nbsp;kbit/s, subtitles 200&nbsp;kbit/s and the data stream, for interactive applications 50&nbsp;kbit/s.<ref name="Freeview HD goes live" /> Recording sizes for Freeview HD television transmissions average around 3&nbsp;GB per hour.<ref>{{cite web | url = http://gonedigital.net/2010/08/12/freeviewhd-bit-rates-and-file-sizes-revisited/ | title = FreeviewHD bit-rates and file sizes revisited | work = Gone Digital | date=12 August 2010 | access-date = 10 May 2011 | first=Nigel | last = Whitfield }}</ref> Between 22 and 23 March 2011, an encoder software change allowed the Freeview version of BBC HD to automatically detect progressive material and change encoding mode appropriately, meaning the channel can switch to 1080p25.<ref>{{cite web|url=https://www.bbc.co.uk/blogs/researchanddevelopment/2011/04/software-upgrade-for-bbc-hd-on.shtml|title=Software Upgrade for BBC HD on Freeview HD|work=BBC|date=5 April 2011}}</ref> This was extended to all of the other Freeview HD channels in October 2011.

To ensure provision of audio description, broadcasters typically use the AAC codec.<ref>{{cite web|url=http://www.reghardware.com/2010/06/02/freeview_hd_surround_sound/|title=Freeview HD sacrifices surround sound for World Cup scramble|publisher=Register Hardware|date=2 June 2010|access-date=22 June 2010|archive-date=6 June 2010|archive-url=https://web.archive.org/web/20100606192312/http://www.reghardware.com/2010/06/02/freeview_hd_surround_sound/|url-status=dead}}</ref> Hardware restrictions allow only a single type of audio decoder to operate at any one time, so the main audio and the audio description must use the same encoding family for them to be successfully combined at the receiver. In the case of BBC HD, the main audio is coded as AAC-LC and only the audio description is encoded as [[High-Efficiency Advanced Audio Coding|HE-AAC]].<ref>{{cite web |url=https://www.bbc.co.uk/blogs/bbcinternet/2010/06/questions_around_surround_soun.html|title=Questions around surround sound on Freeview HD|publisher=BBC|date=4 June 2010}}</ref> Neither AAC nor Dolby Digital Plus codecs are supported by most home AV equipment, which typically accept [[Dolby Digital]] or [[DTS (sound system)|DTS]], leaving owners with stereo, rather than [[surround sound]], output. Transcoding from AAC to Dolby Digital or DTS and multi-channel output via [[HDMI]] was not originally necessary for Freeview HD certification. As of June 2010 the [[Digital TV Group|DTG]] D-Book includes the requirement for mandatory transcoding when sending audio via [[S/PDIF]], and for either transcoding or multi-channel [[Pulse-code modulation|PCM]] audio when sending it via HDMI in order for manufacturers to gain Freeview HD certification from April 2011.<ref>{{cite web |url=http://gonedigital.net/2010/06/02/surrounded-by-questions-freeviewhd/|title=Surrounded by questions|publisher=Gone Digital|date=2 June 2010}}</ref> Thus equipment sold as Freeview HD before April 2011 may not deliver surround sound to audio equipment (some equipment may, but this is not mandatory); later equipment must be capable of surround sound compatible with most suitable audio equipment.

In early February 2011, it was announced that one million Freeview HD set-top boxes had been sold.<ref>{{cite web|url=http://www.cable.co.uk/news/digital-tv-service-freeview-hd-passes-1m-sales-800381182/|title=Digital TV service Freeview HD passes 1m sales|publisher=Cable UK|date=2 February 2011|access-date=2 February 2011|archive-date=5 February 2011|archive-url=https://web.archive.org/web/20110205045520/http://www.cable.co.uk/news/digital-tv-service-freeview-hd-passes-1m-sales-800381182/|url-status=dead}}</ref>